Heat exchanger



K B. RIS

HEAT EXGHANGER April 21, 1936.

6 Sheets-Sheet 1 c s e: a o ca 4 as o o o Filed May 8, 1934 0 o e s INVENTOR WA? 625' J BY I 1 M. M ATTORNEYS K. B. RIS

HEAT EXCHANGER April 21, 1936.

Filed May 8, 1934 6 Sheets-Sheet 2 I VENTOR K. B. RIS

HEAT EXCHANGER April 21, 1935;.

Filed May 8, 1954 6 Sheets-Sheet 5 April 21, 1936. K. B. RIS

HEAT EXCHANGER Filed May 8, 1934 6 Sheets-Sheet 4 INVENTOR 180' oow n o o ATTORNEYS K. B. RIS

HEAT EXGHANG'ER April 21, 1936.

Filed May 8, 1934 6 Sheets-Sheet 5 INVENTOR M 4 ATTORNEYS K. B. RIS

HEAT EXCHANGER April 21,, 1936.

6 Sheets-Shet 6 Filed y 8. 1934 EVA/ ORA 70/?5 CONDENJERS 2 ATTORNEYS paraflinic.

Patented Apr. 21, 1936 UNITED STATES PATENT OFFICE HEAT EXCHANGER Application May 8, 1934, Serial No. 724,506

6 Claims. (01. 257-4236) This invention relates to heat exchangers and more particularly to heat transfer ap aratus suitable for evaporating liquids.

My invention contemplates the provision of an improved evaporator apparatus and it also contemplates the provision of an improved-evaporator-condenser system suitable for a number of industrial purposes and especially suitable for the purpose of recovering valuable solvents sothat they can be used repeatedly for their original purpose. For example, in the fractional extraction of mineral oils it is desirable to use a solvent which must be reclaimed if the process is to be performed at a reasonable cost. The fractional extraction of mineral oil containing both the paraflinic series of hydrocarbons and the various naphthenic series may be accomplished by using a suitable solvent, such as a nitro derivative of an aromatic hydrocarbon, for example, nitrobenzene. The naphthenic compounds are much more soluble in nitrobenzene than the paraflinic hydrocarbons, and accordingly by using nitrobenzene as a solvent it is possible to obtain a partial separation of the naphthenic compounds from the My improved apparatus is especially suitable for recovering the nitrobenzene or equivalent solvent from the various fractions obtained by this extraction process. It is to be understood, however, that my improved apparatus may be employed for many other industrial purposes.

My invention contemplates the use of a series of shallow trays or evaporating pans and the liquid to be evaporated is first supplied to one of these trays and then conducted from one tray toanother. Each tray is provided with heating elements for raising the temperature of the liquid to the desired point. I prefer to employ means whereby the liquid supplied to the trays is caused to how across each tray from side to side or from end to end as the case may be in one or more passes, the liquid being then discharged from one tray to another. I may employ means whereby the liquid to be treated is supplied to at least one of the trays throughout substantially the entire length thereof and whereby the liquid thus supplied to the tray flows across the tray and into a number of discharge pipes which conduct the liquid to a second tray. The liquid may be supplied to one of the trays along one edge and where rectangular trays are employed the liquid may be supplied cither along one side edge thereof or along one of the end edges of the tray. According to one embodiment of my invention the liquid is supplied to one of the trays near one end thereof and the tray is provided with transverse baiiies for causing the liquid to flow back and forth across the tray in a plurality of passes. The liquid to be treated, while passing across each tray, whether arranged for a single pass or multipass flow of the liquid, is subjected to the action of the heating elements distributed in each tray and a partial evaporation of the liquid takes place. The-liquid to be treated thus flows in a relatively thin layer while being subjected to the action of the heating elements in the several trays and this is advantageous for it greatly increases the efficiency of the apparatus; the static-head of the liquid, even on the lower heating elements in each tray, is never great enough to require the use of excessively high temperatures in the heating elements for producing the desired evaporation.

The use of a number of evaporating trays as contemplated by my invention is especially desir-- able because it permits of considerable variation in design to suit a variety of operating conditions and it facilitates the careful regulation of the operating temperatures obtaining at various points within the apparatus. The several trays may be mounted in superimposed relation and so arranged that any one tray may be easily re-- moved for cleaning or repair, without disturbing the other parts of the apparatus. Heating elements of various types may be mounted in the trays and the heating medium may be supplied to the heating elements in various ways. The heating medium, whether steam or some other fluid, may be supplied to all of the heating elements by a common manifold or the like, or if desired, the several heating elements may be maintained at different temperatures by providing separate fluid connections for each group of heating elements.

Several trays are preferably mounted within a shell which may be of cylindrical or other form, and this shell is preferably in direct communication with the shell of a condenser, by means of a nozzle or other form of vapor connection welded or otherwise permanently secured to the evaporator shell and to the condenser shell. Several of these evaporator-condenser units may be provided, the arrangement being such that the liquid being treated is first supplied to one of the evaporators and then conducted from one evaporator to another, and in each succeeding evaporator the liquid may, if desired, be subjected to higher temperatures. The condensates may be withdrawn from the several condensers through sep arate pipe connections, thus producing a frac tional separation of the more volatile constituents of the liquid supplied to the evaporators.

The various objects and advantages of my inventionwill be more apparent upon considering the following detailed description of certain embodiments of the invention illustrated in the accompanying drawings, in which-- Fig. 1 is an end elevation of an evaporatorcondenser unit with the end caps removed to reveal details of construction.

Fig. 2 is an enlarged transverse sectional view of the evaporator shown in Fig. 1,.-Fig. 2 being taken on line 2-2 of Fig. 3. v

Fig. 2a. is a fragmentary transverse sectional view of a modified form of evaporator. N

Fig. 3 is a longitudinal sectional view of the evaporator shown in Figs. 1 and 2, taken on line 3-3 of Fig. 2.

Fig. 4 is an enlarged longitudinal sectional view of the condenser shown in Fig. 1, Fig. 4 being taken on line44 of Fig. 1.

Fig. 5 is a vertical sectional view of another form of evaporator. embodying my invention, this figure being taken on line 5--5 of Fig. 6.

Fig. 6 is a side elevation partly in section, of

the evaporator illustrated in Fig. 5. I Fig. 7 is a horizontal sectional view taken on line 1--'I of Fig. 5.

"Fig. 8 is a vertical transverse sectional view of another form of evaporator embodying my invention, Fig. 8 being taken on line 88 of Fig. 9.

Fig. 9 is a longitudinal sectional view taken on line 99 of Fig. 8.

' Fig. 10 is a fragmentary vertical sectional view taken on line l0lll of Fig. 9, showing details of a header construction.

Fig. 11 is a vertical longitudinal section view of another form of evaporator embodying my invention.

Fig. 12 is a horizontal longitudinal section view taken on line l2--l2 of Fig. 11 illustrating details of construction.

Fig. 13 is a horizontal longitudinal section view of another embodiment of my improved evaporator; and

Fig. 14 is a diagrammatic representation of an evaporator-condenser system embodying my invention.

The embodiment of my invention illustrated in Fig. 1 comprises an evaporator-condenser unit, the evaporator having a cylindrical shell I communicating with the shell 2 of the condenser by means of a connecting passage or nozzle 3 welded or otherwise secured to the two shells. If desired the interconnecting nozzle or conduit 3 may be 1 integral with the cylindrical portion of evaporatorshell I as illustrated in Fig. 2. As illustrated in Figs. 1, 2 and 3, the evaporator shell I encloses a plurality of shallow evaporator trays 4, 5 and G mounted one above another. These trays may be provided with side clips or flanges 1 adapted to engage guide members 8 carried by a pair of brackets 9 mounted one on either side of the shell. Lugs Ill may be provided on the brackets 9 for holding the side flanges I firmly in position on the guides 8. The several trays are thus independently mounted on pairs of guides within the shell, the arrangement being such that any one of the trays may be removed from the shell without removing the other trays. Each of the trays contains a plurality of heating elements, such as the bundle of tubes shown at II. Each tube bundle isconnected to a header l2 with the free ends of the tubes slidably mounted in asupport I3, and if desired an intermediate support l4 may be provided for each tube bundle. The header l2 for each tube bundle may be of any desired construction but it is preferably provided with two to the far end of the apparatus and then returns through the outer tubes to the chambers IS in each of the headers and from these chambers the heating medium is discharged through pipes l9 into a discharge manifold 20 communicating with the discharge pipe 2|.

The oil or other liquid to be treated in the apparatus enters the evaporator through a pipe connection 22 which delivers the liquid to a distributor 23 mounted on theinside of the evaporator shell and extending a considerable distance along the shell. This distributor 23 is provided with a number of discharge ports as shown at 24 whereby the liquid is supplied to the upper tray 4 throughout substantially the entire length thereof. The distributor 23 is located just above the upper tray 4 and extends along one edge of this tray so that the liquid is supplied to the tray at one side thereof. The liquid then flows across the tray to the opposite side where it overflows into the tray 5, the liquid being conducted to the tray 5 through a number of discharge pipes 25. These discharge pipes are provided at several points along the top tray 4. andare preferably mounted in screw-threaded openings in the bottom of this tray. A look nut 26 is provided for each of these discharge pipes, the arrangement being such that the pipes can be adjusted to any desired level and then fixed in the adjusted position by tightening this look nut. The discharge pipes are preferably provided with serrated upper edges and it will be understood that the liquid flows over these edges and down through the several pipes into the tray below, the liquid being supplied to the tray 5 at a number of points along one edge thereof. The liquid flows across the tray 5 and then down through another series of discharge pipes 25' which may be similar in all respects to the discharge pipes 25. The liquid thus enters the bottom tray 6 and flows across this bottom tray and into the discharge pipes 25". The liquid then flows into the bottom of the evaporator shell from which it is withdrawn through the discharge pipe 21.

It will be understood that the oil or other liquid flowing through the evaporator from one tray to another is subjected to the action of the heating elements in the several trays. The volatile constitutents of the liquid are vaporized and the vapor withdrawn from the evaporator shell through the nozzle 3. If desired, the nozzle 3 may be equipped with apparatus (not shown) for separating from the vapor any liquid that may be entrained therein. The vapor from the evaporator is discharged into the condenser shell 2 whereit is condensed by coming in contact with finned tubes 28 through which water or some other cooling medium is circulated. The bundle of tubes 28 is mounted in tube sheets 29 and 30. the tube sheet 29 being fixed to the shell 2 and the tube sheet 30 being slidably mounted within the shell and provided with a return bonnet or cap 3|. The cooling medium may be supplied to the condenser through a pipe connection 32 and discharged through a pipe connection 33.

These pipe connections communicate with a header having partitions 34 and 35 for directing the flow of the cooling medium through the tubes, the arrangement being such that multipass flow of the cooling medium is provided. The several rows of tubes 28 in the condenser shell may be mounted in the manner best illustrated in Fig. 1 so as to provide considerable space between these rows of tubes at the side of the condenser shell where the vapor enters. I

- The modified form of evaporator illustrated in Fig. 2a is similar in all respects to that illustrated in Figs. 1, 2 and 3 except for certain details relating to the distributor for supplying liquid to the top tray and relating to the manner in which the trays are secured to the guides on which they are mounted. It will also be noted that the guides in Fig. 2a are somewhat difierent from these shown at 8 in Fig. 2. In Fig. 2a the shell I carries a distributor 36 communicating with the liquid supply pipe 22, and this distributor 36 consists of a liquid receptacle 3'! formed by the end of the pipe 22 which is mounted so that it projects into the shell I and this receptacle delivers the liquid to'a pair of distributlngpipes, one of which is shown at 38. These two distributing pipes extend in opposite directions longitudinally of the shell and are provided with downwardly projecting branches terminating just above the top tray 4 and near one side edge thereof, whereby the liquid is supplied to this tray at a plurality of points along this edge.

In Fig. 2a thesupporting guides 39 for the trays are carried directly by the shell instead of on a supporting bracket, such as that shown at 9 in Fig. 2. The side flanges ofthe trays are clamped to the guides by a plurality of bolts 40 having laterally bent ends engaging the upper surfaces of the sideflanges on the trays.

the nuts 4! on the ends of the bolts, which project through the supporting. guides 33.

p the shell by any suitable means such as the bolts of concentric tubes 5|, the outer tube being pro- 46. The tube sheet 43 carries a number of superimposed shallow trays 41. The trays may be arranged in such a manner that they are supported at one end by the tube sheet 43 to which they may be welded or otherwise permanently secured, and at the other end by a number of supports 48 carried by the shell 42. The header 44 is provided with a chamber 49 serving as a manifold for supplying a heating medium to heating elements located within the several trays. A supply pipe for this heating medium is shown at 50 and serves to deliver the heating medium to the chamber 69. The heating elements in the several trays are illustrated as being in the form vided with an external helical fin to increase its effective heat conducting surface. The inner tubes are in communication with the chamber 49 at one end, and at the other end they are in direct communication with the outer tubes as best illustrated in Fig. 7. It is thus apparent that the heating medium. from the chamber 49 flows lengthwise through the heating elements to The bolts may be secured in position by tighteningthe remote ends thereof and then back to the header 44 where the heating medium is collected in asecond chamber 52 from which it is discharged through a pipe 53. The flow of the heating medium through the heating elements thus occurs in the same manner as in the apparatus illustrated in Figs. 1, 2 and 3, the arrangement being such that a substantially uniform temperature may be maintained throughout the entire length of each heating element. The hot fluid in the inner tubes delivers some of its heat to the fluid returning to the header in the outer tubes.

In the apparatus illustrated in Figs. 5, 6 and 7 the oil or-other liquid to be treated may be supplied to the evaporator shell through one or more supply pipes 54 and 55. The supply pipe 54 delivers the liquid to the upper surface of an inclined plate 56 secured to the wall of the shell and arranged so that it discharges the liquid into the top tray throughout substantially the entire length thereof and along one side of the tray. The liquid then flows across the tray and overflows onto a second plate 51 which serves to supply the liquid to the second tray throughout substantially the entire length thereof, as indicated by the arrows in Fig. 5. Additional plates 58, 59 and 60 conduct the liquid to the lower trays and it will be unders ood that the liquid overflows from the bottom tray into the bottom of the evaporator shell from which it may be withdrawn through the discharge pipe Bl. The vapor formed within the evaporator shell may be withdrawn through a suitable pipe connection 62, preferably located near the top of the shell.

The form of evaporator illustrated in Figs. 8, 9 and 10 is similar to that illustrated in Figs. 1 2 and 3 in that it comprises a horizontally disposed evaporator she l 63 having a vapor discharge nozzle 64 which may conduct the vapor frcm the evaporator to a condenser (not shown). The shell 63 encloses a plurality of shallow trays 65, 66 and 61 having lateral flanges engaging guide supports 68, 69 and 10 res ectively, carried by the shell 63. Theseveral trays are provided with heating elements in the form of tube bundles H, 12 and 13. The tube bundle II is secured to headers 14 and 75 located at opposite ends of the tray 65, and in like manner the two bundles 12 and 13 are secured to headers 16, TI. 18 and I9 respectively. The tubes are preferably provided with external helical fins. The header I4 is provided with a supply pipe for delivering steam or some other heating medium to the header, and with a discharge pipe 8| for discharging the heating medium from this header after it has passed through the tube bundle II. The header 14 is provided with a central partition 82 wh ch prevents by-passing of the heating medium from the supply pipe 80 to the discharge pipe 8!, thus compelling the heating medium to flow through the'tube bundle 1|. Theheaders 16 and 18 may be of the same construction as the header l4. It will be noted, however, that the header 16 is provided with a separate supply pipe 83 for delivering the heating medium to the header and in like manner the header 18 is provided with a separate supply pipe 84 for delivering the heating medium to this header. The headers 16 and 18 are each provided with discharge pipes 85 and 86 respectively, for discharging the heating medium from these headers after it has passed through the tube bundles l2 and 13. Each tube bundle is thus provided with its own separate source of heating fluid and accordingly heating media of different temperatures may be supplied to the several tube bundles.

The liquid to be treated may be supplied to the top tray 65 through a supply pipe 85 communicating with a distributing pipe 86 extending longitudinally of the shell and having a. number of discharge ports 81. The arrangement is preferably such that the liquid is supplied to the top tray along one side edge thereof, the liquid then flows across the tray in heat exchanging relation to the tube bundle therein, and overflows into the tray 66 through a number of discharge pipes 88. These discharge pipes may be vertically adjustable whereby thelevel of the liquid in each tray may be changed as desired. A second series of discharge pipes 89 delivers the liquid from the tray 66 to the bottom tray 61 from which the liquid overflows into the bottom of the shell 63 through a number of discharge pipes 90. The liquid may be withdrawn from the shell through a discharge pipe 9| The form of evaporator illustrated in Figs. 11 and 12 is similar to that illustrated in Figs. 1, 2 and 3 except for the form of the heating elements, the manner in which the liquid is supplied to the several trays and except for the provision of means whereby the liquid flows across each tray in a number of passes. In Figs. 11 and 12 the evaporator shell I I I encloses three shallow superimposed trays H2, H3, H4 mounted within the shell in a manner similar to that described in detail in connection with Figs. 1 to 3.inclusive. Each tray contains a number of heating elements each heating element being in the form of a U-shaped tube which may be provided with external fins as illustrated at H6. The ends of each of the U-shaped tubes in tray I I2 communicate with separate chambers H1 and H8 in a header H9 and it will be understood that the U-tubes in trays H3 and Ill communicate with similar chambers in the headers I20 and I2I associated therewith. The several chambers II1 are connected to a supply pipe I22 for delivering a heating medium such as steam or the like to the heating elements in the several trays. In like manner the several chambers -I I8 communicate with the discharge manifold I23 which serves to collect the heating medium from the several U-tubes and to discharge the same from the apparatus through a discharge pipe I 24.

In the evaporator of Figs. 11 and 12 the liquid to be treated is supplied to the apparatus through a pipe I25 which communicates with the distributor I26. This distributor may be mounted on the inside .of the shell and extends along one side edge of the top tray, the arrangement being such that the liquid is delivered to this tray along this edge and near one end of the tray. A pair of bafiles I21 and I28 are mounted within the tray and arranged so that the liquid flows across the tray from one side to the other in anumber of passes and the liquid is then discharged from the top tray through a plurality of discharge pipes I29. It will be understood that the trays I I3 and I I4 are similarly provided with transverse bafiles for causing the multipass fiow of the liquid and the liquid is discharged from tray II3 into tray II4 through a number of discharge pipes I30. The liquid is then discharged into the bottom of the evaporator shell through a number of discharge pipes I3I. The liquid residue is withdrawn from the shell through a discharge pipe I32.

The form of evaporator illustrated in Fig. 13 is similar to that illustrated in Figs. 11 and 12 in that the liquid to be treated is supplied to the top tray near one end thereof and each tray is provided with a number of heating elements in the form of U-shaped tubes I38, the ends of which communicate with chambers in headers located at one end of each tray. In Fig. 13 the evaporator shell I33 may contain a number of trays as illustrated in Figs. 11 and 12. One of these trays is shown at I34 and this tray is provided with a number of heating elements in the form of Ll-shaped tubes I38, the two legs of each tube being arranged in a substantially horizontal plane, whereas, in the embodiments illustrated in Figs. 11 and 12 the two legs of each tube are arranged in a vertical plane. In Fig. 13 the distributor I35 receiving the liquid to be treated through the supply pipe I36 extends across one end of the tray I34 and it is provided with a number of discharge ports for supplying the liquid to the tray throughout substantially the entire length of this end portion of the tray. The liquid to be treated then flows in intimate heat exchanging relation with the U-tubes in the tray, in a direction parallel with these tubes until it is finally discharged into the next tray through a. plurality of discharge pipes I 31 located at the end of the tray opposite the distributor I35. It will be understood that the heating elements I38 communicate with chambers in the header I39 which are connected with a supply pipe I40 for the heating medium and with the discharge pipe I4I for this medium, in a mannersimilar to that described in detail in connection with Figs. 11

. tion illustrated in Figs. 8, 9 and 10 is particularly advantageous for this construction makes it possible to maintain the several tube bundles at different temperatures as may be desired. This is due to the fact that each tube bundle is provided with its own separate fluid connection for the steam or other heating medium, and each tube bundle may be provided with its own discharge pipe for the heating medium.

In Fig. 14 I have illustrated an evaporator-- condenser system embodying my invention. Each evaporator-condenser unit is preferably of the type illustrated in Fig. 1 or in Fig. 8, it being understood that the arrangement of the units with the pipe connections therefor may be varied considerably without departing from my invention, Fig. 14 being merely a diagrammatic representation of an operative system embodying certain features of my invention. In Fig. 14 the several evaporator-s are shown at 92 to 91 inclusive, and the separate condensers associated therewith areshown at 98 to I03 inclusive. The several evaporators are interconnected by suitable pipe connections, such'as those illustrated at I04, and it will be understood that the liquid to be treated may be supplied to the evaporator 92 through a pipe connection I05 and discharged from theevaporator 91 through pipe connection I06. The vapor formed in each evaporator may be conducted to the condenser associated therewith through a suitable passage such as that illustrated at I01, and a condensate discharge pipe is provided for each condenser, as illustrated at I08. One or more ejector manifolds such as those illustrated at I09 and I I0, with suitable pipe connections communicating with the condenser shells, may be provided for the purpose of connecting the condensers to ejectors whereby the several evaporator-condenser units may be operated under a vacuum, thus reducing the boiling point of the volatile liquid supplied to the apparatus. The several evaporators are connected in series and it will be understood that the arrangement of the units is such that a fractional separation of the volatile constituents of the liquid being treated may be efiected. The liquid in passing through the series of evaporators may be subjected to progressively higher temperatures as may be desired.

In the event that the pressure employed in the evaporators 92 to 95 inclusive is different from that employed in evaporators 96 and 91 a loop sealed connection, or the like, may be em ployed between evaporator 95 and evaporator 95.

"It is to be understood that my invention is not limited to the, particular embodiments thereof illustrated and described in detail, but includes such modifications thereof as fall within the scope of the appended claims. For example, while I prefer to have each tray independently removable from the evaporator shell it is nevertheless entirely feasible to have the trays arranged in such a manner that they can all be removed simultaneously. In some installations it may be desirable to have a. separate condenser for each evaporator as explained above, but in other installations it may be more desirable to have one condenser for condensing the vapor from two or more of the evaporators.

I claim:

1. Apparatus of the type described, comprising a, shell, a plurality of superimposed shallow trays within said shell, a plurality of heating elements within each tray and secured thereto, means for supplying a heating medium to said heating elements, means for supplying a liquid to one of. said trays, and means for discharging liquid from one tray to another, said trays with the heating elements therein, being independently removable from said shell.-

2. Apparatus of the type described, comprising an evaporator having a shell and a stack of shallow trays therein and means in said trays for evaporating a liquid therein; and means for directly connecting the shell of the evaporator with a condenser for conducting vapor from said evaporator to said condenser, said connecting means having an inlet substantially coextensive with said stack of trays.

3. Apparatus of the type described comprising a shell, a plurality of superimposed shallow trays within said shell, means within said trays for heating a liquid, means for supplying a liquid to the top tray, and a plurality of plates secured to said shell, each plate being arranged to conduct liquid overflowing onto the same from a tray above said plate, into the tray below said plate.

4. Apparatus of the type described comprising a shell, shallow tray means within said shell and comprising a bottom-plate for supporting a shallow body of liquid, a plurality of heating tubes mounted in said tray means, a header communicating with said tubes and secured to said plate, means for supplying a heating medium to said header, and means for supplying a liquid to said tray means so that it comes in contact with said tubes.

5. Apparatus of the type described comprising a shell, shallow traymeans within said shell and comprising a bottom plate for supporting a shallow body of liquid, a plurality of heating tubes mounted in said tray means, a header. communicating with said tubes and secured to said plate, means for supplying a heating medium to said header, and means for supplying a liquid to said tray means so that it comes in contact with said tubes; said header, heating tubes and tray means beieng removable as a unit from said shell.

6. Apparatus of the type described comprising a shell, tray means within said shell comprising a bottom plate and marginal liquid retaining walls, one of said walls comprising a header, a

plurality of heating tubes in said tray means and communicating with said header, means for supplying a heating medium to said header, and

means for supplying a liquid to said tray means.

KENNETH B. RIS. 

